Manufacture of bipyridyls

ABSTRACT

A process for the manufacture of bipyridyls which comprises heating a bipiperidyl or a substituted pyridine derivative wherein the substituent is a piperidyl group or an open-chain group containing one or more nitrogen atoms, in the vapour phase at a temperature of at least 200* C. in the presence of a dehydrogenation catalyst.

United States tent Bowden June 27, 1972 MANUFACTURE OF BIPYRHDYLS Inventor: Roy Dennis Bowden, Runcorn, England Assignee: Imperial Chemical Industries Limited,

London, England Filed: April 22, 1970 Appl. No.: 31,016

Foreign Application Priority Data [56] References Cited UNITED STATES PATENTS 2,765,310 10/1956 Horrobin ..260/290 P 2,765,311 10/1956 Horrobin et a1. ..260/29O P Primary Examiner-Alan L. Rotman A ttorneyCushman, Darby & Cushman [57] ABSTRACT A process for the manufacture of bipyridyls which comprises heating a bipiperidyl or a substituted pyridine derivative wherein the substituent is a piperidyl group or an open-chain group containing one or more nitrogen atoms, in the vapour phase at a temperature of at least 200 C. in the presence of a dehydrogenation catalyst,

9 Claims, N0 Drawings MANUFACTURE OF BIPYRIDYLS This invention relates to the manufacture of bipyridyls, notably 4,4'-bipyridyls.

According to the present invention we provide a process for the reaction products by known techniques. For example the gaseous reaction product can be condensed and the bipyiidyl isolated from the condensate by solvent extraction and/or fractional distillation, if desired under reduced pressure. If the the manufacture of bipyridyls which comprises heating the reaction product i pv yl e the P ct mixture corresponding substituted pyridine derivative or bipiperidyl in h h t the py y IS the f f I hydrate the vapor phase in the absence of oxygen and ammonia at a Whlch 1S Solld and can sepafated y filtratlon- I temperature of at least 200 C. in the presence of a P F of the Invention y P 'Pq the h pyrl yl dehydrogenation catalyst, the substituted pyridine derivative directly y P a pfp yi Py Wher h having as substituent a piperidyl group or a group of th atom of the piperidyl nucleus is substituted, for example it cargeneral formula C(R)(R,)(R wherein R represents a fies an alkyl S P P piperidyl Py can be f y hydrogen atom, a halogen atom, a hydroxy group, an alkoxy verted to the bipyiidyl in a subsequent dehydrogenation reacgroup and an amino group, R represents a group of the era] formula CN, CON R )or CH The process can be carried out batchwise but has the adaq xR wherein g R4, Rszand :1; 2: represefits 2 l5 vantage that it can becarried outasacontinuous operation, It hydrogen atom or an alkyl, alkene, aryl, alkaryl, aralkyl or Pamcularly u1table for the Production 9 i y yi cycloaliphatic group, and R represents a group as defined in alfhollgh other isomers; for examine 2,2 w n ,4 respect of R or a group of the general formula CH,,(XR,) py fg can be Obtained by Sultable cholce of the Star 2 CH ,(XR wherein X represents an atom of oxygen or mate" sulp hur, n 0, l or 2 and m is l or 2, and R, and R each The invention is illustrated but in no way limited by the folrepresents a hydrogen atom or an alkyl, alkene, aryl, alkaryl, l wing examples: aralkyl or cycloaliphatic group.

The substituent of the substituted pyridine derivative may EXAMPLES 1 to be in the 2-, 3- or 4-position in the pyridine nucleus, and in the The experimental procedure in each example was as case where the substituent is a piperidyl group this may be atlows:

tached to the pyridine nucleus in the 2-, 3- or 4-position in the A catalyst bed was prepared from a pelleted form of the i eridyl nucleus. th h catalyst (see below) to the specified depth in a vertical glass The substituted pyndme denvanve vapor p ase ls reactor tube of internal diameter 1 inch. The tube was fitted heated at a temperature of at least 200 C. in the presence of with a can" a1 thermocouple pocke and contained Raschig the dehydrogenation catalyst. Preferably the temperature is at rings above the catalyst bed The Raschig rings did not 0 O O I q example 9 The suPstltined completely fill the tube. The tube was positioned in a vertical pyndme denvanve can be P 'i P by heating It i furnace maintained at the appropriate temperature. the required temperature and if desired this can be effected in The substituted py was dissolved in water r thanol the presence dehydtogqnanon Preferably 35 (see the table below) and the solution was fed to the top of the however, the yridine derivative is vaporized pr or t Co reactor tube where it was va orized on contact with the ing it with the catalyst and in this case vaporization is con- Raschig rings The vapors pa ed downwardly throu h 'Vienientl), effected by dropping the pyndme denvanve a the catal st bed The va ors were mixed with nitro en fir stream of droplets on to a hot surface, for example in a 883 e g'rou hihe Cam] it bed g vaporizer. Some of the pyridine derivatives are tacky, viscous 40 p reactorgemuem is c ensed and the condensate if liquids or solids at ordinary temperatures and these are con- 1i id (as in the mabmy of the ex erimems) was anal zed b veniemly i i a scfflvenltfpnor to vaponzatlon' 3 g slliquid chromatt igraphy using s t andard techniques Wher: ples of suita e so vents or t is purpose are wa er an i cohols, especially lower aliphatic alcohols and particularly :2: 533221 3 25221]? 222 was dlssolved methanol and th 1, d tra s-h dro enation solvents for exam le $12132 ;itrzb enzene and ben zene. V p In the table the catalyst is designated by a reference letter The pressure at which the substituted pyridine derivative is or heated can conveniently be atmospheric, although higher or PP? f h g lower pressures may be employed if desired. A technique t -t g tls A g t y P2 86" l had which we have found to be particularly useful is to pass the Tea 3 W1 3 m1X uTe 0 7 roger! 5 minute) an yridine derivative in the vapor phase continuously through a g g s mlS/I11111 1ute) for g at :1 5 bed of the catalyst contained in a glass tube. a! piercezict: p agnllmfilr; percent umma/ 0 percent An deh dro enation catalyst may be employed, ad- Umma-SI 1C8 e S vanta g eouslz in i finely divided form. The catalyst may be The reaction conditions and results are shown in the table supported or unsupported, although we prefer to employ a 55 below, in which l?ilutions and Solvent referto the startsupported catalyst so as to promote intimate contact of the tug material which s vaporized. v

Con-

Temver- Bed pera- Dilu- N 2 Sim Catalength ture Time tions (mL/ per- Example No. Pyridine derivative lyst (inches) 0.) (min.) (g./ml.) Solvent mm.) cent 1 1 4- 4- d 1 er'd' 3 350 150 4. 6/50 OH OH 200 63 2 3-i4-ggidi lli-ii fi -bi s t l i r iiethylarninopentane 3 340 95 4.3/50 H 0 500 23 3 3-(4-pyridyD-5-diethylaminopentan-Lol 3 350 50 1.1/25 H 0 500 12 4 3-(4-pyridyD-5-d1ethylammopentaneJ-thwl... A 3 380 48 1.1/25 011 011 2 500 7 5 3-(4-pyridyl)-1, 5-bi s dimethylaminopentane B 3 350 40 1.1/25 H 0 500 13 6 4-(2-pyr1dyD-piper1din0 C 6 375 40 1 32/25 CI-hOH 500 10 1 Conversion is to 4,4-bipyridyl in Examples 1 to 5 and to 2,4-bipyridyl in Example 6.

substituted pyridine derivative with the catalyst. Examples of What we claim i suitable catalyst are nickel, cobalt, copper, chromium, copper chromite, chromia, noble metals notably platinum or palladium, or oxides of noble metals. Examples of suitable-catalyst supports are alumina, silica, silica-alumina and magnesia.

The bipyridyls produced by the process can be isolated from up to 450 C. in the presence of a supported or unsupported dehydrogenation catalyst selected from the group consisting of nickel, cobalt, copper, chromium, copper chromite, chromia, and noble metals or their oxides and whereby the support is selected from the group consisting of alumina, silica, silica-alumina and magnesia, the substituted pyridine derivative having as substituent at piperidyl group or a group of the general formula C(R)(R )(R wherein R represents a hydrogen atom, a halogen atom, a hydroxy group, a lower alkoxy group or an amino group, R represents a group of the general formula CH CN, CH CON(R;,CH 'CH N(R -,)(R wherein R R R and R each represents a hydrogen atom or a lower alkyl or lower alkylene group, and R represents a group as defined in respect of R or a group of the general formula CH,,(XR -'CH,,,(XR wherein X represents an atom of oxygen or sulphur, n is O, l or 2 and m is l or 2, and R and R each represents a hydrogen atom or a lower alkyl or lower alkylene group. 2. A process as claimed in claim 1 wherein the temperature is at least 300 C.

3. A process as claimed in claim 2 wherein the temperature is from 350 to 450 C.

4. A process as claimed in claim 1 wherein the substituted pyridine derivative or bipiperidyl in the vapor phase is ob-,

tained by vaporization of a solution of the substituted pyridine derivative or bipyridyl.

5. A process as claimed in claim 4 wherein the solution which is vaporized is an aqueous solution.

6. A process as claimed in claim 4 wherein the solution which is vaporized is a solution in methanol.

7. A process as claimed in claim 1 wherein the substituted pyridine derivative or bipiperidyl is vaporized in the presence of the dehydrogenation catalyst.

8. A process as claimed in claim 1 wherein the substituted pyridine derivative or bipiperidyl in the vapor phase is diluted with nitrogen gas.

9. A process as claimed in claim 1 wherein the catalyst is employed in a finely-divided form.

unn4- A..- 

2. A process as claimed in claim 1 wherein the temperature is at least 300* C.
 3. A process as claimed in claim 2 wherein the temperature is from 350* to 450* C.
 4. A process as claimed in claim 1 wherein the substituted pyridine derivative or bipiperidyl in the vapor phase is obtained by vaporization of a solution of the substituted pyridine derivative or bipyridyl.
 5. A process as claimed in claim 4 wherein the solution which is vaporized is an aqueous solution.
 6. A process as claimed in claim 4 wherein the solution which is vaporized is a solution in methanol.
 7. A process as claimed in claim 1 wherein the substituted pyridine derivative or bipiperidyl is vaporized in the presence of the dehydrogenation catalyst.
 8. A process as claimed in claim 1 wherein the substituted pyridine derivative or bipiperidyl in the vapor phase is diluted with nitrogen gas.
 9. A process as claimed in claim 1 wherein the catalyst is employed in a finely-divided form. 